'Security incident' at Nevada nuclear site

(CNN) -- Emergency officials responded Tuesday to a "security incident" at the Nevada National Security Site, a dispatcher there told CNN.

The dispatcher did not want to be identified.

A news release from the National Nuclear Security Administration, datelined Las Vegas, says, "Emergency responders are currently responding to an incident on the central portion of the Nevada National Security Site. More information will be released as it becomes available."

At 1,375 square miles, the site is larger than Rhode Island. It has been the site of more than four decades of testing of nuclear weapons.

Congress created the NNSA in 2000 as a semi-autonomous agency within the U.S. Department of Energy responsible for enhancing national security through the military application of nuclear energy.

According to the site's website, "NNSA maintains and enhances the safety, security, reliability and performance of the U.S. nuclear weapons stockpile without nuclear testing; works to reduce global danger from weapons of mass destruction; provides the U.S. Navy with safe and effective nuclear propulsion; and responds to nuclear and radiological emergencies in the U.S. and abroad."